1. Field of the Invention
The present invention relates to a method of designing reflective surface of reflector in vehicle lamp which is used for such vehicles as automobiles.
2. Description of the Related Art
A vehicle lamp is comprised of a light source, reflector, and lens. In such a vehicle lamp, a light from the light source enters the reflective surface of the reflector. This incident light is reflected at each segment of the reflective surface in a reflecting direction which is determined by the surface shape of the respective segment, is transmitted through the lens, and is emitted to outside the lamp.
In such designing of a vehicle lamp, not only the conditions from the aspect of the functions of a lamp (functional constraints), but also the conditions from the aspect of shape to be used in a state mounted on such a vehicle as an automobile (shape constraints), and the conditions from the aspect of appearance (appearance constraints), are imposed. Therefore it is demanded to design a lamp that satisfies the constraints of the required shape and appearance first, then optimize the conditions from the aspect of function.
The functional constraints are, for example, light uniformity, so that the entire lamp illuminates uniformly, and the light diffusion, so that light is appropriately diffused and illuminates in various directions, depending on the type of lamp. The shape constraints are, for example, the conditions due to the capacity and shape of the lamp housing section of the car body, and the shape of the outer face of the lamp (outer surface of the lens) which continues with the other parts of the car body. The appearance constraints are, for example, the conditions due to the balance with the appearance of the other parts of the car body and the requirements in the design aspects of the car body.